Radio Astronomy Ganesh Sankaranarayanan Graduate Student Electrical Engineering

UW Campus Observatory Built in 1892 Located on 4 th and University St Moved in 1895 to the current location Second Building on campus next to denny hall

Telescope 6-inch Brashear objective lens Warner & Swasey equatorial mount 90-inch focal length Warner & Swasey wooden, rests on 3 civil war era cannon balls!

Visible World

Electromagnetic spectrum Electromagnetic radiation The visible world (We see very little!) Radio spectrum X-ray, UV,IR spectrum

History of Radio Astronomy Serendipity? Karl Jansky –1928 Rotating Telescope

History of Radio Astronomy Grote Reber meter dish antenna Image courtesy NRAO

Radio Sources 21-cm Neutral Hydrogen Lines 21-cm photon High Energy StateLow energy state

Radio Sources 21-cm Neutral Hydrogen lines Discovery Emission once in few million years 80% Hydrogen in Universe 21-cm emission not obstructed by dust Used to map galaxies and ISM Harold Irving Ewen 1951

Milky Way in 21cm Image courtesy of NRAO/AUI

M33 Radio and Optical Composite Image courtesy of NRAO/AUI and NOAO/AURA/NSF

Orion Nebula M42 Image courtesy of NRAO/AUI

Radio Sources Pulsars Discovered in 1967 Rapidly rotating neutron star km radius Cosmic clocks in the sky First thought to be a signal from aliens (“little green men”) Image courtesy Jodrell Bank Pulsar Group

Sounds of Pulsars PSR B PSR B PSR B , The Crab Pulsar 47 Tucanae Image and sound courtesy Jodrell Bank Pulsar Group

Pulsar and Supernova Remnant Image courtesy of NRAO/AUI

Crab Nebula Pulsar Image Courtesy J. Hester (ASU), CXC, HST, NRAO, NSF, NASA

Radio Sources Quasars Quasar : Quasi- stellar radio source Most distant object to emit radio waves Contain super massive black holes in the center Radio emission produced by synchrotron radiation Reflect the stage of universe billions of years ago

Quasar Image courtesy of NRAO/AUI

Radio Sources MASERS Dense molecular clouds with strong emission (T > 10 6 K) MASER action Microwave Amplification by Stimulated Emission of Radiation OH,H 2 O,SiO, CH 3 CH 2 OH and more…

Water MASER Image courtesy of NRAO/AUI

Radio Sources Cosmic Microwave Background Radiation Arno Penzias and Robert Wilson 1963 Robert Wilson on cosmic noise Image and sound courtesy Lucent Technologies Inc.

Cosmic Microwave Background Radiation COBE The COBE datasets were developed by the NASA Goddard Space Flight Center under the guidance of the COBE Science Working Group and were provided by the NSSDC.

Radio Sources Sun Image courtesy of NRAO/AUI

Radio Sources Planets Saturn Jupiter during impact of comet Shoemaker- Levy 9 Image courtesy of NRAO/AUI

Radio Telescopes Arecibo Located in Puerto Rico Operated by Cornell and NSF 1000 ft (304.8 m) Used for Astronomy, atmospheric and planetary studies

Radio Telescopes Green Bank Telescope Located in Green bank, West Virginia 485 feet tall -- taller than the Statue of Liberty! 100 by 110 m width World’s Largest steerable radio telescope Image courtesy of NRAO/AUI

Radio Telescopes VLI (Very Large Array) Located in Socorro, NM 27 antennas interferometer Each antenna 25 meters( 82 feet) in diameter Image courtesy of NRAO/AUI

VLBI (Very Large Baseline Array)

ALMA The Atacama Large Millimeter Array Atacama desert, Chile 64 radio telescopes 12 meter (39 feet) wide dish antenna Expected to operate in 2011 Image courtesy of NRAO/AUI

Radio Telescopes around the world Europe  Westerbork Synthesis Radio Telescope (WSRT), Netherlands  The Ryle Telescope, United Kingdom Australia  Mopra Observatory Asia  Giant Meterwave Radio Telescope(GMRT), India  Nobeyama millimeter array,Japan

Radio Astronomy at UW UAI established in ft dish Currently building motion control and receivers for 21cm hydrogen lines (1420 MHz)

Future of Radio Astronomy More cost to build radio telescopes  Consortium among countries to build future telescopes Major advancements in telescope technologies  Better design to control noise over effective area  GMRT,ALMA  Better angular resolution Encroachment of radio frequencies by ground and satellite communications  More power in deciding frequency allocations  Better modulation techniques to prevent spill over

The End Questions ? Thank You